Accelerated soil and river bank erosion, especially at higher altitudes, can be due to:
- an increase in visitor numbers – damage from walkers and skiers;
- the use of new technology – bulldozing of hill tracks by earth movers;
- political incentives – land drainage;
- poor land management – overgrazing by deer and sheep, badly managed muirburn.
This can lead to large volumes of silt, sand and gravel being washed out and into streams. This material can have various impacts once it reaches the streams, particularly affecting fish populations by:
- infilling the spaces between larger bed material and reducing cover for fish;
- clogging and compaction of the bed, increasing egg washout and damaging spawning areas.
Although many rivers in the central core of the Cairngorms National Park are affected, the extent of the damage is not known, nor how recent a phenomenon it really is.